One vertex per element, one color per generator, with an edge from x to x·s.
(1,2,4,6)(3,5,7,8)(9,10,15,16)(11,14,19,24)(12,17,22,23)(13,21,20,18)(25,26,30,32)(27,34,29,31)(28,36,38,33)(35,39,37,40)(3,7)(5,8)(9,11,15,19)(10,14,16,24)(12,13,22,20)(17,21,23,18)(25,27,30,29)(26,31,32,34)(28,37,38,35)(33,40,36,39)(1,2)(3,5)(4,6)(7,8)(10,16)(11,19)(13,20)(17,23)(26,32)(31,34)(33,36)(39,40) involution — undirected(1,3)(2,5)(4,7)(6,8)(9,12)(10,17)(11,20)(13,19)(14,18)(15,22)(16,23)(21,24)(25,28)(26,33)(27,35)(29,37)(30,38)(31,39)(32,36)(34,40) involution — undirected(1,2)(3,5)(4,6)(7,8)(9,13,15,20)(10,18,16,21)(11,12,19,22)(14,23,24,17)(25,26)(27,34)(28,33)(29,31)(30,32)(35,40)(36,38)(37,39)(9,14)(10,19)(11,16)(12,21)(13,23)(15,24)(17,20)(18,22)(25,29,30,27)(26,31,32,34)(28,35,38,37)(33,40,36,39)A Cayley diagram is a choice, not a fact about the group. Another drawing of this group — in a book, or on a different generating set — may look nothing like this one.